What is the diagnosis and recommended treatment for a patient presenting with a swollen and red right foot, pain at the ball of the foot, and hyperuricemia (elevated uric acid level)?

Acute Gout Flare: Diagnosis and Treatment

This presentation is highly consistent with acute gout—a swollen, red, painful foot with the ball of the foot involved and a serum uric acid of 8.80 mg/dL strongly suggests monosodium urate crystal deposition causing an acute inflammatory arthritis. 1, 2

Diagnostic Assessment

Joint aspiration with synovial fluid analysis for monosodium urate (MSU) crystals under polarized light microscopy is the gold standard and should be performed if feasible, as it provides definitive diagnosis with sensitivity and specificity approaching 100%. 1, 2 The crystals appear needle-shaped and negatively birefringent. 2

However, if joint aspiration is not feasible in your clinical setting, a clinical diagnosis is acceptable given the highly suggestive features present: 1, 2

• Acute onset of severe pain and swelling reaching maximum intensity within 6-24 hours 1
• Erythema (redness) over the affected area 1
• Involvement of the forefoot (ball of foot includes metatarsophalangeal joints, a classic gout location) 1
• Hyperuricemia at 8.80 mg/dL (well above the saturation point of 6.8 mg/dL where MSU crystals form) 1, 3

Critical Diagnostic Caveat

Do not rely on the elevated uric acid level alone to diagnose gout—hyperuricemia is present in many people who never develop gout, and conversely, some patients with crystal-proven gout have normal uric acid during acute attacks. 1, 2 The clinical picture combined with hyperuricemia makes gout highly likely, but crystal confirmation remains ideal. 1, 2

If septic arthritis cannot be clinically excluded, joint aspiration with Gram stain and culture is mandatory, as gout and septic arthritis can coexist. 1, 2

Imaging Considerations

If joint aspiration cannot be performed and the diagnosis remains uncertain, ultrasound is the preferred initial imaging modality, looking for the "double contour sign" on cartilage surfaces (74% sensitivity, 88% specificity for MSU crystal deposition). 1, 2 Dual-energy CT has higher sensitivity (85-100%) and specificity (83-92%) but is more expensive and involves radiation exposure. 1, 2

Plain radiographs have limited value for diagnosing acute gout flares but can help rule out other conditions. 1, 2

Immediate Treatment for Acute Flare

Initiate anti-inflammatory therapy immediately with one of the following options: 2

First-Line Options:

1. Low-dose colchicine: 0.6 mg twice daily (or 1.2 mg once daily) is as effective as higher doses with fewer gastrointestinal side effects 2

2. NSAIDs: Full anti-inflammatory doses (e.g., indomethacin 50 mg three times daily, naproxen 500 mg twice daily) if no contraindications exist 2

3. Corticosteroids: Prednisone 30-40 mg daily for 5-7 days, particularly useful if NSAIDs and colchicine are contraindicated 2

Do NOT start or adjust urate-lowering therapy during an acute flare—this can paradoxically worsen and prolong the attack. 2 If the patient is already on urate-lowering therapy, continue it. 2

Risk Factor and Comorbidity Assessment

Systematically evaluate for risk factors and associated conditions: 1, 2

• Medications: Diuretics (relative risk 1.72), low-dose aspirin, cyclosporine, tacrolimus 2, 4
• Chronic kidney disease (relative risk 4.95)—check creatinine and eGFR 2, 4
• Obesity (relative risk 3.81) 2, 4
• Hypertension (relative risk 3.93) 2, 4
• Cardiovascular disease, heart failure, diabetes, dyslipidemia 1, 2
• Dietary factors: Excess alcohol (especially beer and spirits), meat, shellfish, high-fructose corn syrup, non-diet sodas 1, 2

Long-Term Management Planning

Once the acute flare resolves, initiate urate-lowering therapy with allopurinol, starting at 100 mg daily and increasing by 100 mg weekly until serum uric acid is maintained below 6.0 mg/dL (below the saturation point of 6.8 mg/dL). 5, 3 The typical maintenance dose is 200-600 mg daily, with a maximum of 800 mg daily. 5

Adjust allopurinol dosing for renal impairment: 5

• Creatinine clearance 10-20 mL/min: 200 mg daily maximum
• Creatinine clearance <10 mL/min: 100 mg daily maximum
• Creatinine clearance <3 mL/min: extend dosing intervals

Provide prophylactic anti-inflammatory therapy (low-dose colchicine 0.6 mg daily or low-dose NSAID) when starting urate-lowering therapy, as fluctuations in uric acid levels can trigger flares. 2 Continue prophylaxis for several months until serum uric acid is at target and the patient has been flare-free. 5

Common Pitfalls to Avoid

• Do not diagnose gout based solely on hyperuricemia—up to 80% of people with hyperuricemia never develop gout 2
• Do not assume normal uric acid excludes gout during an acute attack—uric acid can temporarily drop during inflammation 1
• Do not start allopurinol during an acute flare unless the patient is already on it 2
• Do not miss septic arthritis—if fever, systemic symptoms, or atypical features are present, aspirate the joint 1, 2
• Be aware of allopurinol hypersensitivity syndrome, particularly in patients with renal impairment or certain ethnic backgrounds (HLA-B*58:01 variant)—this has a 25% mortality rate and presents with rash, eosinophilia, fever, and organ dysfunction 1